The invention relates to a process for working a workpiece held between a counterholder and a guide by a clamping force by forming a profile, e.g. precision toothing, in a surface of the workpiece.
Formed recesses, e.g. stamped recesses, in workpieces are generally formed in stamping or precision blanking presses. Here, the workpiece to be worked is clamped between a counterholder and a guide and a ram is guided toward the workpiece, this ram bringing about the stamped impression in the workpiece. The punch is generally guided in vertical alignment toward the workpiece, i.e. in an alignment perpendicular to the surface of the workpiece. Particularly when the intention is to form more difficult profiles in the workpiece, a plurality of stamping steps have to be carried out. When forming precision toothing, for example, three steps are necessary. In a first step, the workpiece is deformed or pressed in on the other side from the actual stamping surface, with the result that the stamped surface flows out of the workpiece opposite the deformation point. In a second step, slots are stamped by means of a punch on whose surface there are geometrically specific stamping members. In a subsequent stamping step, teeth are pressed into the stamped surface by a stamping punch with a profiled end face, the flanks of the slots being formed accordingly. The quality of this precision toothing leaves a lot to be desired, particularly in the case of sawteeth.
The object on which the present invention is based is to develop a method and an apparatus of the type stated at the outset by means of which even relatively difficult profiles can be formed accurately in a workpiece.
The foregoing object is achieved by virtue of the fact that forming takes place at an acute angle to the clamping force.
This method has the advantage that the desired profile is produced in the workpiece in a single working step.
In a first exemplary embodiment, the forming element itself is guided obliquely, ie. guidance is effected with a vertical and an obliquely offset component. In practice, it has been found that, for example, this makes it possible to produce significantly more accurate precision toothing, this being attributable, in particular, to better flow behavior of the stamped material at the tip of the toothing.
The profile produced should be of secondary importance. All manner of profiles, especially toothing, are conceivable. The toothing can be rectilinear or rounded. Moreover, the workpiece surface to be worked does not necessarily have to be flat. The word surface also includes the case where a profile is only stamped in over a narrow angle of the workpiece. Even this angle then forms a surface in the broader sense of the invention.
An apparatus according to the invention for carrying out this method has at least one guide and a counterholder, between which the workpiece to be worked is clamped. The guide or counterholder can be of plate-like or wall-like design or of any other desired design. The essential point is that the forming element, which is guided toward the workpiece at an acute angle, is situated in the guide. On the one hand, this can be accomplished by guiding the forming element obliquely in a corresponding aperture.
In a preferred exemplary embodiment, however, the forming element is assigned as additional wedge drive, which has a wedge surface which interacts with an oblique surface on the forming element. In addition, this forming element slides by means of a further oblique surface on a rising surface within an aperture in the guide, with the result that as the wedge drive moves vertically upward, the forming element rises obliquely and, with its pattern in its end face, produces the profile in the workpiece.
Moreover, the force does not necessarily have to be introduced directly via the tool but can also be applied by means of a hydraulic component.
The best distribution of force between the wedge drive and the forming element is probably obtained when the first oblique surface of the forming element, said oblique surface sliding on the rising surface, encloses an angle of 80 to 100xc2x0 with the second oblique surface, which interacts with the wedge surface on the wedge drive, depending on the length and depth of the stamped impression.
In another exemplary embodiment, a forming element is guided between the counterholder and the guide, in the gap in which the workpiece itself is also clamped fast. This means that, in this case, the forming element produces on the lateral surface of the workpiece a profile which corresponds to a pattern on the forming element.
For the sake of simplicity, the movement of the forming element is once again effected by means of a wedge drive, which is guided in apertures in the counterholder or the guide. Here, a wedge surface of the wedge drive interacts with an oblique surface on the forming element, with the result that the forming element is driven toward the lateral surface of the workpiece.
In another exemplary embodiment of the invention, a profile is formed in the workpiece by a rotary/thrust movement of a corresponding forming element which has the pattern for the profile on its end face. In this case, there is a suitable aperture in the guide, allowing the forming element to move vertically upward in this guide with a simultaneous rotary motion.